This grant proposal is a request for continued partial funding of the Hybridoma Core Facility (HCF) within the Multipurpose Arthritis and Musculoskeletal Disease Center (MAMDC). The primary purpose of the HCF is to produce monoclonal antibodies (Mabs) for members of the MAMDC in as rapid and economical a manner as possible. To this end, the HCF will continue to use procedures which have been successful in the previous granting period to construct rat and mouse hybridomas specific for a variety of protein, carbohydrate, bacterial, viral and cell-associated antigens as outlined in the progress summary. In addition to performing fusions, the HCF is actively involved in research projects designed to improve and expand the services offered to members of the MAMDC. At present, the HCF is attempting to develop chicken hybridoma technology as a means to produce monoclonal antibodies to proteins that exhibit a high degree of evolutionary conservation and thus represent difficult targets for conventional murine hybridoma technology. An additional research interest of the HCF is the production of single-chain antibody fragments (sFvs). These molecules are of special interest because they can be expressed intracellularly in eukaryotic cells and have the ability to downregulate expression of target antigens. These and other research projects initiated by the HCF insure that the laboratory will continue to provide "state of the art" monoclonal antibody technology to members of the MAMDC.